Method of purifying petroleum oils



`luly 19, 1932. D. E. DAY

METHOD OF PURIFYING PETROLEUM OILS Filed June 12, 1929 INVENTOR BY/qV/ t'. .UH Y

ATTORNEY Patented July 1,9, l1932 UNITED STATES DAVID E. DAY, OF LOS ANGELES, CALIFORNIA p,

METHOD OF PURIFYING PETROLEUM OILS Application inea June 12,

This invention relates to an improved process of purifying petroleum oils derived by distillation or cracking of mineral oils, such as lubricating oil stocks, lamp oil dis- 5 tillates, gasoline or naphtha stocks, or distillates derived from shale oil, and more specitically refers to the treatment of gasoline v or naphtha stocks produced by cracking an asphalt or mixed base crude'petroleum oil or .0 distillates derived from relatively high sulphur-bearing crude petroleum oils, in which hydrogen sulphidefmercaptans and otherl sulphur-bearing compounds, as well as varying percentages of phenols and unstable7 hy- .5 drocarbons (such as diolenes and acetylenes) may be present or formed during s aid distillation or Vcracking operation. For the purpose of simplifying the description of my invention, reference will be made to gasoline I` stocks, mainly.

By well-known methods, gasoline stocks derived from cracking petroleum oils or from distilling high sulphur bearing crude petroleum oils, are usually purified by varying l treatments with sulphuric acid, followed by neutralization with a water solution of an alkali, a sweetening-operation and a final distillation. In the sweetening operation, hypochlorite of soda or sodium plumbite'in a wa- IC ter solution of caustic soda may be employed to convert corrosive sulphur compounds into non-corrosive bodies so that the treated gasoline stock will be sweet7 to the doctor test. In these treatments,particularly where 5 hypochlorite of soda is employed, chlorinated hydrocarbons may be formed to a small extent, which may be converted into corrosive compounds during a subsequent distillation. Also, all the sulphur bearing hydrocarbons remaining in the gasoline stock after the purification operation, form corrosive acid compounds during combustion, and if in appreciable amounts, may attack the metal parts of an engine. Therefore, it is advantageous in the purification of gasoline or naphtha stock, to use a purifying agent which in itself will not form chlorinated oils and one which will remove a high percentage of the sulphur compounds'from a gasolinestock and polymerize the unstable 1929. Serial No. 370,325.

hydrocarbons so that they same may be separated therefrom by a subsequent distillation.

Now, I have discovered that a concentrated solution, or a substantially concentrated water solution of acaustic alkali, such as caustic soda, caustic potash, or the carbonates of sodium or potassium, are suitable agents to employ for this purpose on a gasoline or naphtha stock or other petroleum oil distillate, at temperatures between 850 and 500 degrees F., under a pressure sutlicient to prevent any substantial vaporization of the pe troleum oil stock under treatment, by means of which a gasoline stock so treated is rendered sweet to the doctor test, the unstable hydrocarbons are polymerized, ahigh percentage of the sulphur bearing compounds are removed and on distillation a Vpurified gasoline stock is obtained which is water white in color and maybe stored for a 7 period of time without any substantial change in color.

The process described briefly consists in vpassing the hydrocarbon oil product, such as gasoline stock in a liquidphase, commingled with a substantially concentrated water solution of caustic soda or caustic potash, through a heating coil under a pressure suiicient to` prevent any substantial vaporization therein, at a temperature between 350 and 500 degrees F., and then immediately releasing the pres-- sure and separatinvl by distillation the purified gasoline stock from thecaustic` alkali, the extracted impurities and the products of polymerization or condensation.

The hydrocarbon oil to be treated by my invention may or may not have had a preliminary treatment with sulphuric acid, or other agents to partly purify the same, or may be 00 rst partly purified by myinvention and the purification completed by methods known in the art. In the case of gasoline stocks produced by cracking high sulphur bearing .crude petroleum oils or residuums, it may be advantageous to treat such gasoline stocks with sulphuric acid at low temperatures ranging from approximately O to 82 degrees F. before theA treatment with a concentrated water solu- I tion of caustic soda or caustic potash at the by a distillation and fractionation operation to separate the products of reaction and higher boiling polymerized purified gasoline stock.

Another object of the invention is to provide a continuous, rapid and economical proc- 4 ess for purifying gasoline stocks produced by other the thermo decomposition of higher boilingr petroleum oils, by treating the same under super-atmospheric pressure sufficient to maintain a liquid phase with a substantially concentrated water solution of an alkali at temperatures of approximately 350 to 500 degrees F., to polymerize substantially all of the unstable hydrocarbons contained therein, and at the same time remove oxygenated hydrocarbons and render the gasoline sweet to the doctor test.

Another object of the invention is to provide a continuous, economical method for improving the colorand removing gums and gum forming material from gasoline or naphtha stock sothat the same may be kept 1n storage for relatively long periods of time without change in color or quality by the formation of polymerized bodies.

Other objects and advantages will be apparent from the preferred embodiment of this invention which will now be more fully explained by reference to the accompanying drawing which is a diagrammatical representation of an apparatus in which the invention may be carried out.

`In the drawing, 3 represents generally a tank for holding a supply of the gasoline or v petroleum oil stock to be processed. Pipe 1, controlled by the valve 2 connects the gasoline stock tank 3 near the top to a source of supply not shown. Pipe 4, controlled by l valve 5, connects gasoline stock tank 3 to the inlet side of pump 6. ,Pipe 7, connects pump 6 to jet mixer 8. 13 represents generally a caustic soda tank for holding a concentrated solution of a caustic alkali such as caustic soda or caustic potash. Pipel14 controlled by valve 15, connects caustic soda tank 13' near the top to a source of supply not shown. f

Pipe 11, controlled by valve 12 connects caustic soda tank 13 near the bottom to the inlet side ofpump 10. Pipe 9 connects the discharge side of pump 10 to jet mixer 8. Pipe 16, connects the jet mixer 8 to heater coil 38. The heater eoil 38 is stationed in the furnace products from thev escasos 17. rlihe heater 17 is provided with a burner 18 which leads to a supply of fuel not shown.

Pipe 39, controlled by pressure relief valve 19, connects theheater coil 38 todistillation tower 20. The distillation tower 20 is provided with bubble trays 21. Pipe 22, controlled by valve 23, connects the distillation tower 2O near the bottom to a source of water supply not shown. Pipe 25, con-trolled by the valve 24 connects distillation tower 20 at the bottom to tank 26. Pipe 28 controlled by valve 27 connects the tank 26 tol a storage not shown. Pipe 29 connects distillation tower 20 at the top to condenser coil 31. Con- Petroleum oil distillate such as gasoline stock contained in tank 3, is permitted to flow through pipe 4 and into the inlet side `of pump 6,'the rate of flow being governed by operation of valve 5. Pump 6 continuously discharges the gasoline stock under a pressureof approximately 150 to 1000 pounds gauge into jet mixer 8, wherein the gasoline stock is continuously commingled with the necessary quantity of a substantially concentrated water solution of caustic soda or caustic potash coming from the caustic soda supply tank 13. l

The water solution of caustic soda'or caustic potash contained in the supply tank 13 is permitted to tlow through pipe 11 and into the inlet side of pump 10 'which discharges the same under pressure ranging from approximately 150 to l1000 pounds gauge through pipe 9vk and into the said jet mixer 8, the rate of flow being governed by operation of valve 12. l j j The quantity of water solution of caustic soda or caustic bpotash employed may range from as low as approximately 1 per cent to as high as l0 per cent by volume or more, depending upon the stock to be treated.` For example, if a crude gasoline stock contains a high percentage of impurities to be extracted, or has had a preliminary treatment with sulphuric acid, as much as 10 per cent by volume or more o-ia concentrated water solution of caustic soda or caustic potash may be employed. The pressure maintained on the system by means of pumps 6 and l0 is regulated so that the commingled mixture of the water solution of "caustic alkali and gasoline stock under treatment will be maintained in a sub-- stantially liquid phase, such pressure depending upon the boiling points of the gasoline stock and the temperature employed. From vjet mixer 8 the gasoline stock commingled with the water solution of thealkali passes through heater coil 38, pipe 39, pressure relief valve 19, where the pressure is reduced t0 atline stock ata temperature of approximately Y 400 degrees F.; together with a portion of the water content of the alkali solution, are

vaporized and separated fromvthe products of the alkali reaction and the causticI alkali employed. The purified gasoline-stock mixed with water vapor, passes out of distillation tower 20, through pipe 29 into condenser coil 3l stationed in condenser box 30, wherein the said purified gasoline stock and water Vapor are condensed to a liquid, passing through pipe 33 and into the treated gasoline tank 34. lirom the treated gasoline tank 34 the purified gasoline stock may be conducted to a storage not shown, through pipe 36, controlled by Valve 35. The purified gasoline stock so obtained may be thereafter treated,

if necessary, by other `methods known in the art, or may be subjected to a distillation operation to separate fractions having any desired range of boiling points.

The caustic alkali and products of the re- 10 action which separate inthe bottom of dis-4 tillation tower 20 are intermittently or continuously drawn into tank 26 through pipe 25 controlled by valve 24, water being continuously or intermittently introduced into 35 the lower section of distillation tower 20, through the pipe 22, controlled by valve 23, in quantities sufiicient'to replace the vaporized water from the caustic alkali water solution so as to maintain the used caustic alkali and products of the reaction in a fluid condition.

From the tank 26 the excess water Solution of caustic alkali and products of the A reaction are conducted to a storage not shown b5 xthrough pipe 28 controlled by valve 27- and the caustic soda or caustic potash may be separated from the reaction products and recoveredfor re-use.

While the process herein described is well @C adapted for carrying out the objects of this invention, various modifications may be made such as the employment of various fractionating equipment known in the art to effect any desired separation of the treated gaso- .t line stock into fractions having a desired tion of a caustic alkali, passing ,the comrange of boiling points, and the invention includes all such changes and modifications as appear within the scope of the appended claimst What I claim is:

1. A process of purifying naphtha stocks, comprising, commingling a naphtha stock with a substantially concentrated water solution of a caustic alkali, passing the commingled mixture through a. heating coil at temperatures of approximately 350 to 500 degrees F., under a pressure sufficient to prevent substantial vaporizationV therein, then releasing the pressure and separating a purified naphtha stock by vaporzation from products of reaction and excess caustic alkali'.l

2. Av process of purifying naphtha stocks, comprislng, commingling a naphtha stock with a substantially concentrated water solumingled mixture through a heatingr coil at temperatures of approximatelyh350 to 500 degrees F., under a pressure suflicientto prevent substantial vaporization therein, then releasing the pressure and separating by vaporization and fractionation, a purified naphtha stock from products of reaction and excess caustic alkali.

3. A process of purifying naphtha stocks, comprising, contacting'a naphtha stock Vwith 95 a substantially concentrated water solution of a caustic alkali, at a temgeature of approximately 350 to 500 degrees F., under a pressure sufficient to prevent substantial vaporization, then reducing the pressure and separating purified napht a stocks by vaporization and fractionation, rom products of reaction andV excess caustic alkali.

4. A continuous process for purifying gasoline stocks, derived from cracking hlgher boiling petroleum oils, comprising, continuously commingling a gasoline stock with a substantially concentrated water solution of caustic soda, continuously passing the commingled mixture through a' heating element 110 to heat the same to a temperature of approximately350 to 500 degrees F., under a pressure sutlicient to prevent substantial vaporization therein, releasing the pressure and separating by vaporization a purified gasoline stock from products of reaction and excess caustic soda.

5. A process of removing unstable iinsaturated hydrocarbons and corrosive s ulphur bearing hydrocarbons'from Ya gasoline stock containing the sam'e, comprising, con- 120 'tacting the gasoline stock with a substantially concentrated water solution of a caustic calkali, while passing through a restricted assa ewa at temperatures-ranging from 50 togOO ydegiees F., under a pressure suii- RJ cient to prevent any substantial vaporization therein, then reducingl the pressure to approximately atmospheric and separatlng by vaporization a purified gasoline stock from poducts of reaction and excess caustic alkali. L0 I 6. A process of removing gum-forming constituents from cracked gasoline stock, comprising, contacting a cracked gasoline stock with a water solution Aof a caustic alkali at temperaturesl of approximately 350 to 500 degrees F., under a pressure sufficient to prevent substantial vaporization thereof while passing through a heating coil for a period of time suiiicient to cause unstable hydrocarbons contained in the cracked gasov.line stock to polymerize with the formation way of larger diameter, vaporizing9 fractionating, condensing and collecting purified naphtha free from the products of reaction and excess caustic alkali.

8. A continuous process for purifying gasoline stocks derived by the thermo-decom- 'position of higher boiling petroleum oils,

SEE

comprising, continuously commingling a gasollne stock 1n a )et mixer with a water solution of av caustlc alkali, continuously f passing the commingled mixture from the j et mixer through a heating coil to heat the commingled gasoline stock and water solution of caustic alkali to a'temperature of ap-k proximately 400 degrees F., under a pressure suiiicient to prevent substantially vaporization therein, continuously releasing the pressure after the commingled mixture of the gasoline stock and water solution of caustic alkali have passed through the said heating coll at a temperature of approximately d0() degrees continuouslypassing the saine into a vaporlzing tower, continuously vaporizing and separating purified gasoline stock and water vapor from higher boiling reaction products and excess caustic alkali.

9. A continuous process for purifying gasoline stocks derived by the thermo-moleculm-decomposition of higher boiling petroleum oils, comprising, continuously commingling a gasoline stock with a water solution of a caustic alkali, continuously passing the commingled mixture through a heating coil to heat the commingled gasoline stock andY water solution of caustic alkali to a teinperature of approximately 4:00 degrees F., under a pressure sucient to prevent substantial vaporization therein, continuously neevgeoe and introduced water containing excess.

caustic alkali, substantially as described.

l0. A process of purifylng gasoline stock, comprising, contacting a gasoline stock with a water solution of caustic alkali, while passing through a heating coil under a pressure suiiicient to prevent substantial vaporization therein, to heat the said gasoline stock and water solution of caustic alkalito a temperature of approximately 400 degrees F., releasing the pressure after the gasoline stock and Water solution of caustic alkali have passed throu h the said heating coil, separating by vaporlzation purified gasoline stockt, rom higher boiling products of reaction and excess caustic alkali.

ln testimony whereof l aflix my signature.

DAVlD Fi. DAY..

releasing the pressure after the commingled 

